Cell-specific differences in the requirements for translation quality control

TY - JOUR

T1 - Cell-specific differences in the requirements for translation quality control

AU - Reynolds, Noah M

AU - Ling, Jiqiang

AU - Roy, Hervé

AU - Banerjee, Rajat

AU - Repasky, Sarah E

AU - Hamel, Patrice

AU - Ibba, Michael

PY - 2010/3/2

Y1 - 2010/3/2

N2 - Protein synthesis has an overall error rate of approximately 10 -4 for each mRNA codon translated. The fidelity of translation is mainly determined by two events: synthesis of cognate amino acid:tRNA pairs by aminoacyl-tRNA synthetases (aaRSs) and accurate selection of aminoacyl-tRNAs (aa-tRNAs) by the ribosome. To ensure faithful aa-tRNA synthesis, many aaRSs employ a proofreading ("editing") activity, such as phenylalanyl-tRNA synthetases (PheRS) that hydrolyze mischarged Tyr-tRNAPhe. Eukaryotes maintain two distinct PheRS enzymes, a cytoplasmic (ctPheRS) and an organellar form. CtPheRS is similar to bacterial enzymes in that it consists of a heterotetramer in which the α-subunits contain the active site and the β-subunits harbor the editing site. In contrast, mitochondrial PheRS (mtPheRS) is an α-subunit monomer that does not edit Tyr-tRNA Phe, and a comparable transacting activity does not exist in organelles. Although mtPheRS does not edit, it is extremely specific as only one Tyr-tRNAPhe is synthesized for every ∼7; 300 Phe-tRNA Phe, compatible with an error rate in translation of ∼10 -4. When the error rate of mtPheRS was increased 17-fold, the corresponding strain could not grow on respiratory media and the mitochondrial genome was rapidly lost. In contrast, error-prone mtPheRS, editing-deficient ctPheRS, and their wildtype counterparts all supported cytoplasmic protein synthesis and cell growth. These striking differences reveal unexpectedly divergent requirements for quality control in different cell compartments and suggest that the limits of translational accuracy may be largely determined by cellular physiology.

AB - Protein synthesis has an overall error rate of approximately 10 -4 for each mRNA codon translated. The fidelity of translation is mainly determined by two events: synthesis of cognate amino acid:tRNA pairs by aminoacyl-tRNA synthetases (aaRSs) and accurate selection of aminoacyl-tRNAs (aa-tRNAs) by the ribosome. To ensure faithful aa-tRNA synthesis, many aaRSs employ a proofreading ("editing") activity, such as phenylalanyl-tRNA synthetases (PheRS) that hydrolyze mischarged Tyr-tRNAPhe. Eukaryotes maintain two distinct PheRS enzymes, a cytoplasmic (ctPheRS) and an organellar form. CtPheRS is similar to bacterial enzymes in that it consists of a heterotetramer in which the α-subunits contain the active site and the β-subunits harbor the editing site. In contrast, mitochondrial PheRS (mtPheRS) is an α-subunit monomer that does not edit Tyr-tRNA Phe, and a comparable transacting activity does not exist in organelles. Although mtPheRS does not edit, it is extremely specific as only one Tyr-tRNAPhe is synthesized for every ∼7; 300 Phe-tRNA Phe, compatible with an error rate in translation of ∼10 -4. When the error rate of mtPheRS was increased 17-fold, the corresponding strain could not grow on respiratory media and the mitochondrial genome was rapidly lost. In contrast, error-prone mtPheRS, editing-deficient ctPheRS, and their wildtype counterparts all supported cytoplasmic protein synthesis and cell growth. These striking differences reveal unexpectedly divergent requirements for quality control in different cell compartments and suggest that the limits of translational accuracy may be largely determined by cellular physiology.

KW - Amino Acid Sequence

KW - Animals

KW - Humans

KW - Molecular Sequence Data

KW - Phenylalanine-tRNA Ligase

KW - Protein Biosynthesis

KW - Quality Control

KW - RNA, Transfer

KW - Sequence Homology, Amino Acid

U2 - 10.1073/pnas.0909640107

DO - 10.1073/pnas.0909640107

M3 - Journal article

C2 - 20160120

SN - 0027-8424

VL - 107

SP - 4063

EP - 4068

JO - Proceedings of the National Academy of Science of the United States of America

JF - Proceedings of the National Academy of Science of the United States of America

IS - 9

ER -